DISEASES OF PLANTS. 741 



this discoloration is due primarily to oxidization in the presence of a certain 

 moisture content in the wood. Alder wood which is air-dried when white does 

 not become discolored when exposed to the atmosphere. The color body ap- 

 pears to be one of the iron-tannic combinations and oxidization does not take 

 place until the cell walls are destroyed. A microscopic investigation as to the 

 nature of the color body was conducted and is here discussed. 



On the effect of different intervals between successive tappings in Para 

 rubber (Hevea brasiliensis), M. K. Bamber and R. H. Lock {Circs, and Agr. 

 Join: Roy. Bot. Gard, Ceylon, 5 {1910), No. 9, pp. 73-87). — Experiments were 

 started in the Tropical Gardens at Henaratgoda, Ceylon, in 1908 to ascertain 

 what differences, if any, exist in the quantity, composition, and properties of 

 rubber latex drawn from the trees by tappings carried out at different intervals 

 of time. The trees are over 20 years old and planted in squares at a distance 

 of 12 ft. apart. The plan of the experiments is given, together with the results 

 thus far secured. The work is being continued. 



Among the deductions thus far made it appears that the yield from trees 

 tapped daily and from trees tapped weekly is practically identical for the same 

 number of tappings, both in the gross and in proportion to the area of bark 

 tapped. During the first few tappings the percentage of rubber contained in 

 the latex decreases at a rate more or less inversely proportionate to the length 

 of the interval between successive tappings. After a number of tappings have 

 been made, a nearly constant percentage composition of the latex occurs which 

 is lower in the case of trees tapped at short intervals than in the case of trees 

 tapped at longer intervals. The proportion of scrap rubber obtained is lower 

 in the case of the more frequent tappings. 



Mature trees tapped daily for IS months yielded for this period an average of 

 over 7 lbs. of rubber per tree. At the four hundred and fortieth tapping, each 

 tree yielded at the rate of 4 lbs. of dry rubber annually. The trees were quite 

 healthy and showed no signs of having suffered from the severe tapping. From 

 the standpoint of yield alone frequent tappings have given the best results, 

 although from the standpoint of bark recovery the experiments have not been 

 co)iducted sufficiently long to determine whether frequent tapping should be 

 conducted throughout the year or whether the tree should be allowed to rest 

 during certain months. 



Tapping- experiments with rubber trees in Misahohe, Togo, compared with 

 the results of other experiments, Gruner {Tropenpfianser, IJf {1910), Nos. 

 11, pp. 5S7-593; 12, pp. 6J,9-G55; 15 {1911), Nos. 1, pp. 36-39; 2, pp. 101-104).— 

 The results of tapping experiments with various species of rubber are given 

 and compared with those secured with the same species in other rubber-pro- 

 ducing countries. 



Notes on creosoting, A. T. Gillanders {Trans. Roy. Scot. Arbor. Soc, 23 

 {1910), pt. 2, pp. 172-179). — A discussion of the relative merits of the pressure, 

 boiling, and cold-immersion methods of creosoting timber. 



With the view of determining the value of the cold-immersion process, the 

 author conducted tests with 7 kinds of timber comparing it with the pressure 

 process. The data secured indicate that on very small estates the immersion 

 method is the better on account of its simplicity, and that it may be so managed 

 as to be quite successful. 



DISEASES OF PLANTS. 



Report of botanist and plant pathologist, H. W. Baeee (South Carolina 

 Sta. Rpt. 1910, pp. 23-26). — In addition to the continuation of work on cotton 

 anthracuose, sweet potato rots, and on the plant disease survey of the State, 



